From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3D37CC11D05 for ; Thu, 20 Feb 2020 16:03:45 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0A56B20658 for ; Thu, 20 Feb 2020 16:03:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="aX5XdCZj" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0A56B20658 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:44834 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j4oIi-0004GC-7X for qemu-devel@archiver.kernel.org; Thu, 20 Feb 2020 11:03:44 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:53412) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j4oHa-0002Ub-PI for qemu-devel@nongnu.org; Thu, 20 Feb 2020 11:02:35 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j4oHZ-0001VT-Nt for qemu-devel@nongnu.org; Thu, 20 Feb 2020 11:02:34 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:37102 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1j4oHZ-0001VI-JS for qemu-devel@nongnu.org; Thu, 20 Feb 2020 11:02:33 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582214553; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZJpezD2KNFbbDvsoaGK8DPS+dV5Ahk9Qu4SROwnM09s=; b=aX5XdCZjVkN4sFAgQm3W815rAeFG3hh0rOZimNSw9+EHPqtI2BhLZ3mS8eNIpa0JfJubA6 oarSWVCJacmpXBgAkZ+oFlzl9MKR6z2OCwhLT8dMIhxRi7icg04dFW5FIFmEYVfpwBkjWM yj4esyPUElQDy2ljcZrlS+qo8Putys4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-26-gQstA_RvMXKKrWkDIKjioQ-1; Thu, 20 Feb 2020 11:02:25 -0500 X-MC-Unique: gQstA_RvMXKKrWkDIKjioQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 22B818010FD; Thu, 20 Feb 2020 16:02:24 +0000 (UTC) Received: from [10.3.116.180] (ovpn-116-180.phx2.redhat.com [10.3.116.180]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5965F10027A7; Thu, 20 Feb 2020 16:02:23 +0000 (UTC) Subject: Re: [RFC PATCH v3 05/27] qcow2: Document the Extended L2 Entries feature To: Max Reitz , Alberto Garcia , qemu-devel@nongnu.org References: <0b884ddcd0ac3a3c0b8cdd9d09c74566ac107c9a.1577014346.git.berto@igalia.com> <7ff19f65-5148-a40a-9b7a-6a330cf7272e@redhat.com> From: Eric Blake Organization: Red Hat, Inc. Message-ID: Date: Thu, 20 Feb 2020 10:02:22 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <7ff19f65-5148-a40a-9b7a-6a330cf7272e@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , "Denis V . Lunev" , Anton Nefedov , Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2/20/20 9:54 AM, Max Reitz wrote: >> +Subcluster Allocation Bitmap (for standard clusters): >> + >> + Bit 0 - 31: Allocation status (one bit per subcluster) >> + >> + 1: the subcluster is allocated. In this case the >> + host cluster offset field must contain a valid >> + offset. >> + 0: the subcluster is not allocated. In this case >> + read requests shall go to the backing file or >> + return zeros if there is no backing file data. >> + >> + Bits are assigned starting from the most significan= t one. >> + (i.e. bit x is used for subcluster 31 - x) >=20 > I still prefer it the other way round, both personally (e.g. it=E2=80=99s= the C > ordering), and because other places in qcow2 use LSb for bit ordering > (the refcount order). Internal consistency with refcount order using LSb ordering is the=20 strongest reason to flip things, and have bit x be subcluster x. --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org